﻿---
title: Arrays
description: In Elasticsearch, there is no dedicated array data type. Any field can contain zero or more values by default, however, all values in the array must be...
url: https://www.elastic.co/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/array
products:
  - Elasticsearch
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# Arrays
In Elasticsearch, there is no dedicated `array` data type. Any field can contain zero or more values by default, however, all values in the array must be of the same data type. For instance:
- an array of strings: [ `"one"`, `"two"` ]
- an array of integers: [ `1`, `2` ]
- an array of arrays: [ `1`, [ `2`, `3` ]] which is the equivalent of [ `1`, `2`, `3` ]
- an array of objects: [ `{ "name": "Mary", "age": 12 }`, `{ "name": "John", "age": 10 }`]

<admonition title="Arrays with object field type vs nested type">
  Arrays of objects in Elasticsearch do not behave as you would expect: queries may match fields across different objects in the array, leading to unexpected results. By default, arrays of objects are [flattened](/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/nested#nested-arrays-flattening-objects) during indexing. To ensure queries match values within the same object, use the [`nested`](https://www.elastic.co/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/nested) data type instead of the [`object`](https://www.elastic.co/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/object) data type.This behavior is explained in more detail in [`nested`](/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/nested#nested-arrays-flattening-objects).
</admonition>

When adding a field dynamically, the first value in the array determines the field `type`. All subsequent values must be of the same data type or it must at least be possible to [coerce](https://www.elastic.co/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/coerce) subsequent values to the same data type.
Arrays with a mixture of data types are *not* supported: [ `10`, `"some string"` ]
An array may contain `null` values, which are either replaced by the configured [`null_value`](https://www.elastic.co/elastic/docs-builder/docs/2964/reference/elasticsearch/mapping-reference/null-value) or skipped entirely. An empty array `[]` is treated as a missing field — a field with no values.
Nothing needs to be pre-configured in order to use arrays in documents, they are supported out of the box:
```json

{
  "message": "some arrays in this document...",
  "tags":  [ "elasticsearch", "wow" ], <1>
  "lists": [ <2>
    {
      "name": "prog_list",
      "description": "programming list"
    },
    {
      "name": "cool_list",
      "description": "cool stuff list"
    }
  ]
}


{
  "message": "no arrays in this document...",
  "tags":  "elasticsearch",
  "lists": {
    "name": "prog_list",
    "description": "programming list"
  }
}


{
  "query": {
    "match": {
      "tags": "elasticsearch" <4>
    }
  }
}
```

<tip>
  You can modify arrays using the [update API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-update).
</tip>